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Gland

Thyreoid

LR

shows the chief

the neck and also its divergence to the left.

19T THORACIC V.

TD.

thoracic verte

P

thoracic

duct

When seen in sections of the frozen body (Fig. 908), the esophagus usually appears either as a flattened tube with a

Fig. A is at level transverse slit-like cavity, or as an oval or

of the superior rounded canal with a more or less stellate

part lst thoracic

vertebra, and lumen. The former condition is more

OE. common in the neck, owing to the pressure

A relations of the

oesophagus in of the trachea, and the latter in the thorax.

When exposed in the ordinary postmortem examination soon after death, it mas rather the appearance of a solid muscular od or band than of a hollow tube.

The oesophagus presents three distinct onstrictions, one situated at its beginning, nother at the point where it is crossed by

Fig. B, at the 3rd he left bronchus, and the third where it

B bra, shows the asses through the diaphragm. The two pper constrictions are of the same size,

lying on left

side of the cesound will admit without injury an instru

phagus. nent with a maximum diameter of 4 inch 20 mm.). At each of these points the

3rd THORACIC V. ube is flattened from before backwards.

The resophagus varies in length in different ndividuals, from 8 to 14 inches (20 to 35 cm.).

L.B.

R.B. Che distance from the upper incisors to the begining of the wesophagus averages about 6 inches

In Fig. C, at the -5 cm.).

Clevel of the 5th During life the cervical portion is said, under

bra, the rdinary circumstances, to be closed and flattened rom before backwards by outside pressure, whilst ne thoracic portion may be open owing to the egative pressure in the thorax. The passage into

cesophagus. ne stomach is also said to be open (Mickulicz), but nis is doubtful.

5TH THORACIC V. The size at the two constrictions, when the tube fully distended, is 23 mm. transversely, and mm. antero-posteriorly. The other parts vary diameter between 26 and 30 mm. (Jonnesco).

Fig. D is at the In its first curvature to the left the divergence

D greatest opposite the third thoracic vertebra.

A

bra, and shows he second inclination to the left begins about

10

the pericardium

lying on the e seventh thoracic vertebra, and continues to the

anterior surface d of the esophagus, being considerably increased the diaphragm is approached.

phagus.

8TH THORACIC V. Relations of the Esophagus. - The -lations (Fig. 908) differ so widely in the eck and thorax that they must be described

Fig. E, at the 9th parately for each of those regions.

bra, shows the In the Neck.—Anteriorly lies the trachea

oesophagus in. E

clining to the to the posterior membranous wall of

left just before hich the cesophagus is loosely connected by

piercing the

diaphragm. eolar tissue—and in the groove at each de, between the trachea and esophagus, е recurrent nerve ascends to

the rynx (Fig. 908, A). Posteriorly lie the Fig. 908.—TRACINGS FROM FROZEN SECTIONS TO rtebral column and the longus colli SHOW THE RELATIONS OF THE ESOPHAGUS auscles, from which the wesophagus is

[graphic]

thoracic verte.

left bronchus is seen in relation to the anterior sur. face of the

Pc

[graphic]

level of the sth thoracic verte

of the so

[graphic]

thoracic verte.

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at the levels of the 1st, 3rd, 5th, 8th, and parated by the prevertebral layer of the

9th thoracic vertebræ, respectively. rvical fascia. On each side are placed the A, Aorta ; c. Common carotid artery ; D; Diaphragm ; rotid sheath with its contained vessels, and L.R, Left recurrent nerve; L.V, Left vagus ; OE,

Esophagus; P, Pleura ; Pc, Pericardium; R.B, e corresponding lobe of the thyreoid gland Rightbronchus; R.R, Right recurrent nerve; d the inferior thyreoid artery. Owing

R.V, Right vagus; T, Trachea; T.D, Thoracic duct; V.A, Vena azygos.

9TH THORACIC V.

to the deviation of the tube to the left in the inferior part of the neck, its relation to the carotid sheath and thyreoid gland is much more intimate on the left than on the right side.

In the Thorax.—The esophagus passes successively through the superior and posterior mediastina, in the former lying close to the vertebral column, but in the latter advancing somewhat into the thoracic cavity and coming into contact with the back of the pericardium. The trachea still lies anterior to it as far as the fifth thoracic vertebra, where the trachea bifurcates. Immediately below that the cesophagus is crossed by the left bronchus (Fig. 908, C), and in the rest of its thoracic course it lies in the closest relation to the back of the pericardium. Posteriorly, in the upper part of the thorax, it rests on the longus colli muscles and the vertebral column; but below the bifurcation of the trachea, as already explained, it advances into the cavity of the posterior mediastinum, and is soon separated from the vertebral column by the vena azygos, the thoracic duct, the upper five aortic intercostal arteries of the right side, and in its lower part by the thoracie aorta as well.

On its left side, in the upper part of the thorax, lie the left pleura and the left subclavian artery, with the thoracic duct in a plane posterior to the artery; in the middle region, the aorta, and lower down the left pleura again, for a little way, before the esophagus pierces the diaphragm. On the right side the tube comes into relation with the arch of the vena azygos, whilst the right pleura clothes it both below and above that level.

The two vagus nerves, after forming the anterior and posterior pulmonary plexuses descend to the cesophagus, where they form, by uniting with one another and with the branches of the sympathetic, the anterior and posterior oesophageal plexuses. Lower down the left nerve winds round to the anterior, whilst the right turns to the posterior surface of the cesophagus, and in this relation they pass with the tube through the diaphragm to reach the stomach.

The

The diaphragmatic portion, about half an inch in length (1 to 1:5 cm.), corresponds to the portion of the tube which lies in the @sophageal orifice (or canal) of the diaphragm. plane of this orifice is very oblique or almost vertical, and its abdominal opening looks forwar: and to the left, and but little downwards. Above and in front, where it is bounded either by the posterior edge of the central tendon or by a few decussating fibres of the muscular portion of the diaphragm, which meet behind the tendon, the esophageal orifice has practically no length, and consequently the æsophagus here passes into the abdominal cavity immediately after leaving the thorax. At the sides and behind, on the other hand, the decussating bands from the two crura, which embrace the orifice, are so arranged that they turn a flat surface (not an edge. towards the opening, and thus, behind and at the sides, the orifice or canal is of some length; and on these aspects there is a portion of the tube in contact with the diaphragm for a distance of 1 to 11 cm. But this contact takes place not around a horizontal line, but in a very oblique plane corresponding to that of the orifice.

The oesophagus, in passing through the orifice, is connected to its boundaries by a considerable amount of strong connective tissue, but it is extremely difficult, or impossible, to demonstrate any direct naked-eye connexion between the æsophageal muscular fibres and those of the diaphraga.

The anterior or right boundary of the esophageal orifice, formed of fibres derived from bol crura of the diaphragm, is strongly developed and prominent, and usually lies in the esophages. groove, on the back of the left lobe of the liver, which groove is rarely due to the pressure of the cesophagus alone.

The pars abdominalis of the æsophagus is very short, for immediately after piercing the diaphragm the tube expands into the stomach. However, when the empty stomach is draw forcibly downwards, a portion of the front and left side of the tube, about half an inch in length (1 to 1:5 cm.), is seen, to which the above term is applied. This part is covered with peritoneum. derived from the great sac in front and on the left, whilst its right and posterior surfaces are uncovered. It is generally described as lying against the æsophageal groove and the left triangula: ligament of the liver in front, but it never actually comes in contact with the latter of these structures, which is attached to the upper surface of the left lobe of the liver by one edge, and to the diaphragm, over an inch in front of the esophagus, by the other. As regards the former, the æsophageal groove of the liver is generally occupied by the prominent right margin of the æsophageal orifice of the diaphragm and occasionally by the æsophagus as well. Possibly this margin is so strongly developed and so prominent in order that it may bear the pressure of the liver off the gullet, which otherwise might be interfered with in its dilatation during the passage of foci

When the stomach is fully distended the abdominal part of the æsophagus almost disappear being absorbed into the stomach in its distension.

The portion of the æsophagus which adjoins the stomach is sometimes described as consisting of two parts, namely, the ampulla phrenica and the antrum cardiacum. The former 33

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usiform expansion of the tube, of variable length and girth, which lies within the thorax mmediately above the point where the gullet is grasped between the two muscular margins f the resophageal opening and the diaphragm. It lies in the lowest part of the posterior nediastinum where this is bounded anteriorly by the back of the diaphragm.

The antrum cardiacum is another name for the abdominal portion of the esophagus. It is unnel-shaped, and expands towards the stomach.

Relation of the Aorta to the Esophagus.-The arch of the aorta, passing back to reach he vertebral column, crosses to the left side of the esophagus; consequently the descending horacic aorta lies at first to its left; lower down, however, as the aorta passes on to the anterior spect of the vertebral column, and the gullet inclines forwards and to the left, the aorta comes o lie posteriorly, and then, as the diaphragm is approached, it lies not only posteriorly, but also omewhat to the right of the esophagus (Figs. 907 and 908).

Relation of the Thoracic Duct to the Esophagus. - The thoracic duct, lying to the right f the aorta below, is not directly related to the æsophagus (Fig. 908, E); but higher up fig. 908, D and E) it lies posterior to it. About the level of the aortic arch the duct passes to ne left, and above this (Fig. 908, B and A) will be found on the left side of the æsophagus, and a plane somewhat posterior to it.

Relation of the Pleural Sacs to the Esophagus. -Above the level of the arches of the orta and of the vena azygos, between which the esophagus descends, the pleuræ, though ot lying in immediate contact with the esophagus, are separated from it only by a little connecve tissue, and on the left side also, behind the subclavian artery, by the thoracic duct (Fig. 18, B). Here, in thin bodies, the left pleura is very close to the wesophagus, and the thoracic duct, ing on its left side, may occasionally be seen through the pleural membrane. Below the arch the azygos vein the right pleura clothes the right side of the wesophagus—and very often even a nsiderable portion of its posterior surface too, thus forming a deep recess behind it—almost as w down as the opening in the diaphragm. On the left side, below the level of the aortic arch, e left pleura comes in contact with the gullet, only for a short distance, just above the diaphragm ig. 908, E). Variations.—The chief anomalies found in the wesophagus are: (1) Annular or tubular conrictions ; (2) diverticula, of which the most interesting—known as pressure pouches ”—are ually situated on the posterior wall close to its junction with the pharynx, and these somemes require surgical interference ; (3) doubling in part of its course ; and (4) communications etween the trachea and esophagus.

Structure of the Esophagus (Fig. 911).—The esophageal wall is composed of ree proper coats—(1) tunica muscularis, (2) tela submucosa, and (3) tunica mucosa. In dition, it is surrounded by an outer covering of areolar tissue (4) tunica adventitia, by nich it is loosely connected to the various structures related to it in its course. his loose covering permits of its free movement and of its increase in size, or of its minution, during

the act of swallowing. The tunica muscularis is composed of two layers an outer of longitudinal, d an inner of circular fibres. The longitudinal layer is highly developed, and, like the condition usually found in the digestive tube, it is as stout as, or in aces stouter than, the circular layer. Its fibres form along the greater length of the

even covering outside the circular layer, and below they are continued Co the longitudinal fibres of the stomach. Above, near the superior end of the ophagus, the longitudinal fibres of each side, separating at the back, pass round wards the anterior aspect and form two longitudinal bands (Fig. 909), which run up

the front of the tube, and are attached by a tendinous band to the superior part of e posterior surface of the cricoid cartilage (Fig. 909).

The circular muscular fibres, though not forming such a thick layer as the longitudinal res, are nevertheless well developed. Below, they are continued into both the circular d oblique fibres of the stomach. Above, they pass into the inferior fibres of the inferior strictor of the pharynx.

At the superior end of the esophagus the muscular fibres are entirely of the striated riety. Soon unstriped fibres begin to appear in increasing numbers, and in the inferior If or two-thirds only unstriped muscle is found.

The longitudinal fibres for about the superior fifth of the tube are entirely striped ; in e second fifth striped and unstriped are mixed; whilst in the inferior three-fifths unstriped res alone are present. The circular fibres are entirely striated for the first inch; after s unstriped fibres appear; and in the inferior two-thirds, only unstriped muscle fibres e found. The longitudinal fibres are often joined by slips of unstriped muscle, or elastic fibres, ich spring from various sources, including the left pleura (m. pleuro-oesophageus, constant, nningham), the bronchi (m. broncho-oesophageus), back of trachea, pericardium, aorta, etc. ese slips assist in fixing the esophagus to the surrounding structures in its passage through

thorax, and have been aptly compared to the tendrils of a climbing plant (Treitz). The tela submucosa, composed of areolar tissue, is of very considerable thickness, in

be an

order to allow of the expansion of the tube during swallowing. It connects the mucous

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Inferior
constrictor

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Upper border of
cricoid cartilage

Vessels ra the infer zabdomen,

The veins ver mart

teoid cation bet The lymph

Indiastin

-Tendinous band

Ik berres - :he vagus

Circular fibres of esophagus

Longitudinal bands

Longitudinal

Trachea fibres diverging Fig. 909. — DISSECTION to show the

arrangement of the muscular fibres on the posterior aspect of the esophagus and pharynx. Traced upwards, the longitudinal inuscular fibres of the cesophagus are seen to separate posteriorly; passing round to the sides, they form two longitudinal bands which meet anteriorly and are united to the cricoid cartilage, as shown in the next figure.

Fig. 910.—THE INFERIOR PART OF THE PHARIXI

AND THE SUPERIOR PART OF THE ESOPHAGUS bare
been slit up from behind, and the mucous mem-
brane removed to show the muscular fibres. The
two longitudinal bands are seen passing round
to the front to be attached by a common tendon
to the superior border of the cricoid cartilage. See
explanation of last figure.

As the red - cessary t

peritoneu: Ctained wit The abdor costs of a arge cavity

membrane loosely to the muscular coat, and admits of the former

stinuous sm zans mentio > w-called - bent visce

mucosa

mucosæ
Loose conn.

Tela subinucosa

in any P ace of the ca

In the fol date the stoneal cavi

when empty. In this t of the
coat are contained the

numerous racemose
Epithelium | Tunica

mucous glands (glandula Papilla

csophagea) which open Conn, tissue

into the cavity of the muscularis

@sophagus (Fig. 911).

The tunica mucosa
tissue

is of a grayish - pink
Glandula
oesophagea

colour, much paler than

that of the pharynı,
Circular
muscle

and of a firm and resis
tant texture. It is
covered with a thick

stratified, squamous epi-
ganglion

thelium, on the surface

of which the openings Longi

of numerous glands are
tudinal

found. Inferiorly, its
muscle
fibres

junction with the gastric

mucous membrane is Tunica

indicated by a distinct, adventitia

irregularly dentated or

crenated line, which runs Fig. 911.- TRANSVERSE SECTION OF WALL OF HUMAN (ESOPHAGUS. transversely round the

tube. In carefully pre served specimens the smooth mucous membrane of the æsophagus above this line contrasts strongly with the mamillated gastric mucous membrane below.

Owing to the inelasticity of this coat, and the fact that it is but loosely connected to

[graphic]

Shape.-IC

axis dired als flatter se posterior

Tunica muscularis

un transve e no te

13 inches nied by the

The abdom avis minor. pelvis lies belo yanation.

Asbe wal

sendered sepse Boundaries

of the di

e muscular coat by the submucosa, it is thrown into a series of longitudinal folds when ? @sophagus is empty and contracted; hence the stellate lumen often seen in sections the gullet. Glands. – Numerous racemose mucous glands, the glandulæ oesophageæ, large enough e seen distinctly with the naked eye, are found in the submucosa. They are pretty ly distributed over the whole tube, and do not appear to be more numerous towards r end. In addition to these, other glands, resembling closely those of the cardiac end e stomach, are found in the mucous membrane of certain portions of the esophagus. are entirely confined to the mucosa, and do not extend beyond the lamina muscularis w. These glands are specially numerous at both the upper and lower ends of be. sels and Nerves. Its arteries consist of numerous small branches derived, in the neck, e inferior thyreoid, in the thorax, from the bronchial arteries and thoracic aorta, and in omen, from the left gastric artery, and also from the left inferior phrenic. veins form a plexus on the exterior of the esophagus, from which branches pass, in r part of the tube, to the coronary vein of the stomach, and, higher up, to the azygos, eoid veins. There is thus established on the lower part of the oesophagus a free comon between the portal and systemic veins. mph vessels pass to the inferior set of deep cervical glands in the neck, and to the posliastinal glands, many of which, of large size, are seen around the tube, in the thorax. erves are derived from the recurrent, and from the cervical sympathetic in the neck, agus and sympathetic nerves in the thorax.

THE ABDOMINAL CAVITY.

remaining parts of the digestive system lie within the abdomen it will y to describe that cavity, and to refer briefly to its lining membraneeum-before passing on to the consideration of the viscera which are ithin it. omen is that portion of the trunk which lies below the diaphragm. It wall, composed in part of bones, muscles, tendons, fascia, etc., enclosing v, in which lie the greater part of the digestive, urinary, and generative gans, as well as blood vessels, nerves, and other structures. The greater vall of the cavity, and the surfaces of the viscera, are clothed by a ooth membrane, the peritoneum. The cavity is completely filled by the ned. They lie in contact with one another, and when they are in situ cavity is merely a potential space between the peritoneal surfaces of a. When air is admitted, as, for instance, by opening the abdominal ce, the viscera fall away from one another and a space is formed, in billary interval which exists under normal conditions between them. wing description, the term abdomen or abdominal cavity is used to gion enclosed by the muscular and bony walls, and the term

the potential space inside the peritoneal membrane between the eneral shape the cavity is of a somewhat oval form, with the

vertically. The superior end is wider than the inferior. It is from before backwards, and is encroached upon in the median by the projection forwards of the vertebral column. section, it will be noticed that the front of the vertebral column istance from the back of the anterior abdominal wall (usually ile on each side of the vertebral column there is a deep recess, Ineys and portions of the intestine.

cavity is divisible into the abdominal cavity proper and the ical section of the trunk shows that the pelvis minor (O.T. true d behind the abdominal cavity, of which it forms a funnel-shaped long axis of the funnel is directed downwards and backwards. these two regions are markedly different, the boundaries will be y. e Abdomen Proper.—The cavity is limited above by the concave gm, which is dome-shaped and presents a right and a left cupola

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